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Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
LS-DYNA Input
This manual provides a list of LS-DYNA input files available in Radioss.
*CONSTRAINED
*CONSTRAINED_EXTRA_NODES
LS-DYNA Input Interface KeywordDefine extra nodes to add to a rigid body.

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Radioss^® is a leading explicit finite element solver for crash and impact simulation.
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User Guide
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
Reference Guide
This manual provides a detailed list of all the input keywords and options available in Radioss.
- File Extensions and Formats
  Current Radioss format uses the 12x extension format.
- Single File Input
  This format allows running either Starter or Engine with the same file.
- New Keywords in 2025
  New and modified features in Radioss.
- Starter Input
  This manual provides a list of all the model definition keywords and options available in Radioss.
- Engine Input
  This manual provides a list of all the solution definition keywords and options available in Radioss.
- LS-DYNA Input
  This manual provides a list of LS-DYNA input files available in Radioss.
  - *AIRBAG
  - *BOUNDARY
  - *CONSTRAINED
    - *CONSTRAINED_EXTRA_NODES
      LS-DYNA Input Interface KeywordDefine extra nodes to add to a rigid body.
    - *CONSTRAINED_GENERALIZED_WELD_SPOT
      LS-DYNA Input Interface KeywordDefine a connection between 2 nodes with a possible force-based failure model.
    - *CONSTRAINED_INTERPOLATION
      LS-DYNA Input Interface KeywordDefines an RBE3 element.
    - *CONSTRAINED_JOINT
      LS-DYNA Input Interface KeywordDefine a joint between two rigid bodies.
    - *CONSTRAINED_JOINT_STIFFNESS
      LS-DYNA Input Interface KeywordDefine a stiffness, stop angles and friction for rotational DOFs of a joint between two rigid bodies.
    - *CONSTRAINED_NODAL_RIGID_BODY
      LS-DYNA Input Interface KeywordThis keyword defines a nodal rigid body.
    - *CONSTRAINED_NODAL_SET
      LS-DYNA Input Interface KeywordDefines a translational constraint to a set of nodes in the global coordinate system. There is no rotational coupling.
    - *CONSTRAINED_RIGID_BODIES
      LS-DYNA Input Interface KeywordDefine rigid bodies assembly.
    - *CONSTRAINED_ SPOTWELD
      LS-DYNA Input Interface KeywordDefine a connection between 2 nodes with a possible force based failure model.
  - *CONTACT
  - *CONTROL
  - *DAMPING
  - *DATABASE
  - *DEFINE
  - *ELEMENT
  - *EOS
  - *HOURGLASS
    LS-DYNA Input Interface KeywordDefine solid and hourglass formulation for 8-node solid elements.
  - *INCLUDE
  - *INITIAL
  - *INTEGRATION_SHELL
    LS-DYNA Input Interface KeywordDefine user-defined through the thickness integration rules for the composite shell element.
  - *KEYWORD
    LS-DYNA Input Interface KeywordThis keyword should always be the first card of the input file. Optionally used with *CONTROL_UNITS card to specify model units.
  - *LOAD
  - *MAT
  - *NODE
    LS-DYNA Input Interface KeywordDefines a node number and nodal coordinates in the global coordinate system.
  - *PART
    LS-DYNA Input Interface KeywordDefines a part, which combines material and property information.
  - *RIGIDWALL
  - *SECTION
  - *SET
- Multi-Domain
  This manual contains the description of the keywords for the Radioss Multi-Domain.
- Obsolete Keywords
  Keywords that are still supported, but no longer maintained (*) are considered obsolete.
- Other Files
- Definition
Example Guide
This manual presents examples solved using Radioss with regard to common problem types.
Verification Problems
This manual presents solved verification models.
Frequently Asked Questions
This section provides quick responses to typical and frequently asked questions regarding Radioss.
Theory Manual
This manual provides detailed information about the theory used in the Altair Radioss Solver.
User Subroutines
This manual describes the interface between Altair Radioss and user subroutines.

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*CONSTRAINED_EXTRA_NODES

LS-DYNA Input Interface KeywordDefine extra nodes to add to a rigid body.

Format


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
*CONSTRAINED_EXTRA_NODES_OPTION

If OPTION = NODE, insert the following line.


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`part_ID`	`node_ID`	`Iflag`

If OPTION = SET, insert the following line.


(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)
`part_ID`	`set_ID`	`Iflag`

Definition


Field	Contents	SI Unit Example
`OPTION`	Entity type. NODE A list of nodes is SET.
`part_ID`	Part identifier of the rigid body defined as a rigid material. (Integer)
`node_ID`	Node identifier to add to as a secondary node to the rigid body. (Integer)
`set_ID`	Node set identifier to add to as a secondary nodes to the rigid body. (Integer)
`Iflag`	Flag for merged rigid body property (used if `part_ID` is PART_INERTIA). = 0 Default Rigid body center of gravity, mass and inertia is recomputed with all merges rigid bodies. = 1 Rigid body center of gravity, mass and inertia keeps the value defined in `part_ID`. (Integer)

Comments

This keyword maps to /MERGE/RBODY.